Permutations

Permutations.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace CSharpRough
{

    class Program
    {
        static void Main(string[] args)
        {
            List<ArrayDimensions> dimensions = new List<ArrayDimensions>()
            {
                new ArrayDimensions(){StartIndex = 1, Count = 9},
                new ArrayDimensions(){StartIndex = -5, Count = 9},
                new ArrayDimensions(){StartIndex = 5, Count = 3}
            };
            foreach (var indices in GetIndices(dimensions))
            {
                Console.WriteLine(string.Join(",", indices));
            }
            //Console.ReadKey();
        }

        public static IEnumerable<int> Prepend(int first, IEnumerable<int> rest)
        {
            yield return first;
            foreach (var item in rest)
                yield return item;            
        }
        static IEnumerable<T> Singleton<T>(T first)
        {
            yield return first;
        }
        public static IEnumerable<IEnumerable<int>> GetIndices(List<ArrayDimensions> dimensions)
        {
            if (dimensions.Count == 0)
                return Singleton(Enumerable.Empty<int>());

            return from first in Enumerable.Range(dimensions.First().StartIndex, dimensions.First().Count)
                   from rest in GetIndices(dimensions.Skip(1).ToList())
                   select Prepend(first, rest);

        }
    }
    public class ArrayDimensions
    {
        public int StartIndex { get; set; }
        public int Count { get; set; }
    }
}